Centrifugal pump



CENTRiFUGAL PUMP Filed Sept. 18, 1935 2 Sheets-Sheet l M M M M w m N E m wh +m 4. B ///////yX wx/X4/ fi/kK/Q/T 5 ///////M////// I W Y MMHHHHI MHHW. u/ QV m l I/ r\ x E W C l v WM H k a. v l .P v N mmu MMH! ll, ///////////i\ R fi M N EV 6 NM. N a SN R y 1937- A P. BROCKLEBANK 7 2,086,975

CENTRIFUGAL PUMP Filed Sept. 18, 1935 2 Sheets-Sheet 2 IN V EN TOR.

H135 ATTORNEY.

Patented July '13, 1937 UNITED STATES CENTRIFUGAL PUMP Arthur P. Brocklebank, Elizabeth, N. 1., assignor to IngersolL-Rand Company, Jersey City, N. 1., a corporation of New Jersey Application September 18, 1935, Serial Ni. 41,044

Claims. (01. 103-408) This invention relates to pumps, and more particularly to a, high speed centrifugal pump of the multi stase type.

Examples oi specific uses of a pump constructed 5 in accordance with the invention are the removal of water from a chamber subjected to a high vacuum, as for instance, condensate from a surface condenser, or liquid from a vessel in which the pressure approximates the vapor pressure of the liquid.

In installations of this nature it is essential that the pump be located at a lower level than the source of the liquid so that the liquid will enter the pump under pressure, thereby avoiding cavitation and its deleterious effects on the pump parts. However, owing to the restricted head room available in certain locations it is sometimes a diflicult matter to so arrange the elements of a pumping system as to assure sum-.

the overall height of the pump necessitates the arrangement of the source of liquid at a considerable elevation. Obviously, this requires an increased height of a proposed building to house the system or, as isfrequently' the 'case, costly alterations toan existing building toaccommodate It.

In view of the foregoing considerations I propose to so construct a pump of a given capacity as to permit of its arrangement in a comparatively small space and which will operate in a highly emcient manner and at speeds well within known safe limits. This I accomplish through. a definite division of work between stages of which theflrst stage consists of two impellers, each having capacity for handling one half the 49 total volume of liquid pumped. The impeller may, therefore, be provided with small inlet openings or eyes and, for that reason, he of small ,diameter, so that they may be operated safely at high speeds. This is also true of the succeed- 5 ing stage impellers and. the pump may, in consequence, be constructed of. low overall height.

With the pump thus constructed, the first stage impeller performs a comparatively small amount of work and serves mainly, when employed under 5 conditions above enumerated, to deliver the liqwe to the succeeding stage impeller at a pressure that will enable the succeeding stage impeller to function at maximum emciency.

It is an object of the invention to enable a high- 515 speed centrifugal pump to be operated emciently in the plane of the longitudinal axis of the shaft and without danger of an interruption in the continuity of the column of supply liquid. as through cavitation for example. i

Another object is to maintain the rotary element of the pump in hydraulic balance and thereby prevent a destructive end thrust of said element.

Still another object is to enable a pump intended for relatively high capacity output to be readily adapted for use in locations in which there is restricted head room.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawings accompanying the specification and in which similar reference numerals 15 referto similar parts,

Figure 1 is a longitudinal elevation, in section, of a pump constructed in accordance with the practice of the invention, and

Figures 2 and 3 are transverse views taken through Figure l on the lines 2-2 and 3-3, respectively.

Referring more particularly to the drawings, 2t designates a pump'comprising a casing 2| having bearings 22 at its ends to support a shaft 23 extending through the pump and through packing glands M in the ends of the casing. The casing 2| consists of'an, upper section 25 and a lower section 2%. The sections abut each other 23 and maybe secured together in any wel 0 known and suitable manner.

The pump 20 is of the multi-stage type comprising in the present instance three impelling stages of which an intermediate stage impeller 21 is arranged on the shaft 23 in one end of the casing 2! and a final stage impeller 28 is keyed to the shaft 23 in the opposite end of the casing. These impellers are encased, respectively, in, volutes 29 and 3t defining discharge chambers 3i and 32 for the impellers.

The discharge opening 33 of the discharge chamber 3i opens into a passage 34 extending through the lower portion of the casing section 25 to convey the discharge output of the impeller 2'! to the inlet eyes 35 of the final stage impeller 28; In the side of the volute 30 is the final discharge opening 36..

, The impellers 2'5 and it are arranged on the shaft in such wise that their inlet eyes are directed toward the interior of the pump. These impellers have the same fio'w capacity and are. suitably proportioned so that the forces acting against one impeller tending to thrust the rotary element endwise are balanced by the forces actinlet chamber 40 for the impeller 21.

rotary element in hydraulic balance.

The initial impelling stage consists, in the arrangement shown, of two double suction impellers 31 placed side by side on the shaft 23 between the impellers 21 and 28. The impellers 31 are separated by a diaphragm 38 which forms a. bounding surface for inlet chambers 39 through which liquid flows to theinnermost inlet eyes of the impellers31, and between the intermediate stage impeller 21 and the adjacent impeller 31 is a similar diaphragm 38 tocooperate with the casing 2| for defining an inlet chamber 39 for the said adjacent impeller 31 and also an Likewise, between the impeller 28 and the impeller 31 adjacent thereto is a diaphragm 38 which defines an inlet chamber 39 for the outermost end of the impeller 31 and an inlet chamber 4| for the impeller 28.

From the foregoing it will be seen that each end of the impellers 31 is provided with an individual inlet chamber and in order to assure a uniform volume of liquid to all the chambers 39 the casing, in this instance the lower section 26, is provided with an inlet opening 42 which is common to all the inlet chambers 39 and in direct communication therewith.

As has been previously stated, the pump to which the present invention pertains is intended to operate at high speeds. In order, therefore, to avoid the possibility of the inlet chambers of the initial propelling, stages from becoming vapor bound when used for pumping hot condensate or of breaking the continuity of the liquid columnto the initial impelling stage through other causes the impellers 31 are of small diameter as compared with the succeeding stage impellers.

Owing to their comparatively small diameters the impellers 31 operate at less capacity than the v higher stage impellers 21 and 28 as is, of course,

understood. Their peripheral velocities being low the head developed by the impellers 31 will, consequently, be materially less than the pressure rise of the liquid passing through the impellers 21 and 28. Hence a greater number of impellers 31 are employed to assure the delivery of an ample volume of liquid to the succeeding stage impeller, in this instance the intermediate stage impeller 21.

The impellers 31 discharge into a passageway 43 which extends longitudinally through the casing section for conveying the liquid to the inlet chamber 40 of the intermediate stage 1111-.

peller. The passageway 43 extends along the side and over the top of the impellers 31, and. the outer wall 44 of the casing defining it, and which constitutes the intermediate portion of the casing section 25 may, therefore, be held to a low elevation, as for instance below the elevation of the 'volute 29'. This is extremely desirable in structures of this character for the reason that the pump is thereby adapted for use in locations or positions in which the head room is restricted.

In order to further safeguard against the possibility of the pump becoming vapor bound each inlet chamber 39 is provided with a vent 45 positioned at or near the outer portions of the inlet chambers. The vents 45 open into a common chamber 46 in the casing section 25, and to the outlet opening 41 of the chamber" is connected a pipe 48 for conveying such air and uncondensible gases to a desired destination, for example,

ing against the other impeller to maintain the to the condenser to which the pump 20 is connected to remove the condensate.

The operation of the pump, briefly described,

' is as follows: The liquid being pumped, such as condensate, passes through the inlet opening 42 to all the inlet chambers 39 of the initial stage impellers and passes at low velocity through the impellers 31, thence through the passage 43 to the intermediate stage impeller 21. Upon being discharged from the impeller 21 the liquid flows through the discharge opening 33 into andthrough the passage 34 to the final stage impeller, thence through the final discharge open ing 36 to its destination.

Upon entering the inlet chambers 39 any air and uncondensible gases which become separated from the liquid pass through the vents 45, the chamber 46 and the pipe 48 to the condenser and the inlet chambers 39 may, therefore, remain constantly filled with liquid so that the column of supply liquid will remain unbroken.

I claim:

1. A multi-stage centrifugal pump comprising a casing having a pair of sections, a plurality of initial stage impellers grouped in the intermediate portion of the casing, said casing having an inlet opening communicating with all the said impellers, an intermediate stage impeller on one side of the group of initial stage impellers, a final stage impeller on the other side of the group of initial stage impellers, a passage in one casing section for conveying the discharge output of all the initial stage impellers to the intermediate stage impeller, a passage in the other casing section for conveying the discharge output of the intermediate stage impeller to the final stage impeller, and a discharge opening for the final stage impeller.

2. A multi-stage centrifugal pump comprising a casing consisting of an upper section and a lower section, a plurality of initial stage impellers grouped in the intermediate portion of the casing, said casing having an inlet opening communicating with all the said impellers, an intermediate stage impeller in one end of the casing, a final stage impeller in the other end of the casing, a passage in the upper casing section for conveying the discharge output of all the initial stage impellers to the intermediate stage impeller, a passage in the lower casing section for conveying the discharge output of the intermediate stage impeller to the final stage impeller, and a discharge opening for the final stage impeller.

3. A multi-stage centrifugal pump comprising a casing, an intermediate stage impeller in one end of the casing, a final stage impeller in the other end of the casing, a pair of double suction initial stage impellers between the intermediate and final stage impellers and being of relatively small diameter, an inlet opening in the casing communicating with all the initial stage impellers, a passage in the casing to convey the discharge output of both initial stage impellers to the intermediate stage impeller, a passage in the casing to convey the discharge output from the intermediate stage impeller to the final stage impeller, and a discharge opening for the final stage impeller.

4. A multi-stage centrifugal pump comprising a casing, an intermediate stage impeller in one end of the casing, a final stage impeller in the other end of the casing, a pair of initial stage impellers between the higher stage impellers and being of relatively small diameter, an inlet opening in the casing, individual inlet chambers for each initial stage impeller and each inlet chamber communicating with the inlet opening, there being vents in the casing to convey uncondensable gases from the inlet chambers, a passage in the casing to convey the discharge output of both ini-- tial stage impellers to the intermediate stage impeller, a passage in the casing for conveying the discharge output of the intermediate stage impeller to the final stage impeller, and a discharge opening for the final stage impeller.

5. A multi-stage centrifugal pump comprising a casing, an intermediate stage impeller in one end of the casing, a final stage impeller in the other end of the casing, a pair of initial stage double-suction impellers between the higher stage impellers and being of relatively small diameter, an inlet opening in the casing, individual inlet chambers for each inlet side of the initial stage impellers and each inlet chamber communicating with the inlet opening, there being vents in the casing for the escape of uncondensable gas from the inlet chambers, a passage in the upper portion of the casing for conveying the discharge output from all the initial stage impellers to the intermediate stage impeller, and a passage in the lower portion of the casing to convey the discharge output of the intermediate stage impeller to the final stage impeller.

ARTHUR P. BROCKLEBANK. 

